GLUTARYL-COA DEHYDROGENASE (GCDH), AN ENZYME COMMON TO LYSINE, HYDROXYLYSINE, AND TRYPTOPHAN CATABOLISM, CATALYZES THE CONVERSION OF GLUTARYL-COA TO CROTONYL-COA. LACK OF GCDH ACTIVITY IN HUMANS IS CHARACTERIZED BY EXCRETION OF MASSIVE AMOUNTS OF GLUTARIC ACID AND 3-HYDROXYGLUTARIC ACID, THUS GULTARIC ACIDURIA (GA), AND IS USUALLY FATAL. THE PHYSIOLOGICAL ASSAY FOR GCDH ACTIVITY INVOLVES A SECOND ENZYME, ELECTRON TRANSFER FLAVOPROTEIN (ETF). COMMERCIAL AVAILABILITY OF ETF WOULD FACILITATE NEWBORN SCREENING FOR GA AND FOUR OTHER INBORN ERRORS OF FATTY ACYL-COA METABOLISM. COMMERCIAL AVAILABILITY OF GCDH SHOULD ENHANCE BASIC AND CLINICAL RESEARCH, INCLUDING STUDIES OF THE MOLECULAR BASIS OF GA AND DEVELOPMENT OF A FAST METHOD FOR PRENATAL DIAGNOSIS AND CARRIER TESTING FOR GA. PHASE I WILL INCLUDE THE PURIFICATION OF ETF FROM PORCINE LIVER AND THE PURIFICATION OF GCDH FROM HUMAN LIVER. IN PHASE II, GCDH WILL BE USED TO PRODUCE MONOCLONAL AND POLYCLONAL ANTIBODIES. GCDH WILL ALSO BE SEQUENCED, ENABLING THE PRODUCTION OF AN OLIGONUCLEOTIDE PROBE. THE AVAILABILITY OF ANTIBODIES SPECIFIC FOR GCDH WILL ALLOW AFFINITY CHROMATOGRAPHY SCALE-UP OF GCDH PRODUCTION AND WILLBE USED IN CONJUNCTION WITH THE OLIGONUCLEOTIDE PROBE TO ISOLATE CDNA PROBES. THE NEW PROBES WILL BE USED TO DEVELOPA FAST ASSAY FOR PRENATAL DIAGNOSIS AND CARRIER SCREENING.